1. Field of the Invention
The present invention generally relates to a degradation determining system for an exhaust gas cleaning catalytic converter configured to be arranged in an exhaust passage of an internal combustion engine and having at least an oxidizing function (includes NOx trapping catalytic converters).
2. Background Information
One example of a known catalytic converter degradation determining system is the system disclosed in Japanese Laid-Open Patent Publication No. 02-030915. That system (dual O2 sensor system) has two air-fuel ratio sensors (O2 sensors), one arranged upstream of the catalytic converter and another arranged downstream of the catalytic converter. This catalytic converter degradation determining system is configured to determine if the catalytic converter is degraded based on signals from the air-fuel ratio sensors.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved degradation determining system. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.